The term “variegated glass” refers to ornamental glass made by incompletely mixing two or more different colored glass components while they are in the molten state. Typically a primary molten glass may be heated in a furnace and then supplied to a mixing channel. One or more different colored glasses are also heated and supplied to the mixing channel to mix with the primary molten glass. Typically, the combined molten glass is mixed at the end of the mixing channel by a human operator by using a stirring rod. The mixture of molten glass is then fed into a pair of forming rollers to form a variegated glass sheet.
U.S. Pat. No. 4,133,666 to Rhodes, disclosing a method and apparatus for making variegated glass in a continuous sheet, is incorporated herein by reference.
Colored glass tiles made by one technique of the prior art, are made by painting or silk screening an artistic pattern with colored glass enamel (a first layer) on the back of clear glass (a second layer). The colored paint or colored silk screen pattern (the first layer) is then fused with heat on to the clear glass (the second layer). (See for example U.S. Pat. No. 6,607,809 to Baker-Salmon.) In this prior art technique there are only two distinct layers one on top of the other and the color (the first layer) is not distributed through the clear glass (the second layer) but rather lies only on top of or underneath the clear glass.
In another technique of the prior art, the first layer of colored glass enamel may be sandwiched between the second layer of clear glass and a third layer of clear glass. However, as in the first technique, the color (the first layer) is not distributed through the clear glass (second and third layers) but rather lies only on top of or underneath the clear glass.